Industry sources said about 100 fishing boats displaced from the closed areas are now fishing in an area to the east of Shetland and throwing back up to 10 dead juvenile haddock for every one they land.

 One fisherman said : "The cod conservation plan has turned into a haddock destruction plan." According to industry estimates, boats from the main Scottish ports are throwing back 1,000 tons a day of dead undersized young haddock, while landing no more 250 tons.

 Some reports suggest that fishermen have landed only 20 boxes of fish out of 400 caught, with the rest returned dead to the water. Fishermen say that they have been forced by the emergency closures to catch juvenile fish to make a living, but even their own organisations are critical of the move, saying that the haddock was one of the few hopes the industry had of rebuilding itself.

 John Goodlad, the chief executive of the Shetland Fishermen's Association, said: "There is no doubt that there has been a displacement of effort as a result of the cod closure areas that effort is now focused on the juvenile haddock stock to the east of Shetland. There is a huge level of discarding. The real tragedy is that the one bright prospect we face is that the year class of 1999 spawned haddock could form the basis of a haddock fishery for many years to come. If we destroy it now we've blown it."

 He added: "Even allowing for a 100 per cent exaggeration in the numbers of fish being discarded it is still absolutely unacceptable. This is a British thing. There are so many things that we can blame on other Europeans. On this occasions we can't. It's the British fleet that is decimating the juvenile haddock."

 The association and the Scottish Fishermen's Federation say the 12-week closures of cod areas in the northern North Sea must be accompanied by a tie-up scheme that pays fishermen not to fish. Dr Ian Duncan, the federation's secretary, said: "It is very short-sighted to fish in areas where fishermen know there are substantial numbers of juvenile fish. But this is an inevitable consequence of closing large areas without providing other areas to fish or a tie-up scheme."

 He said the effect of closing areas to protect cod would not have been a success if it brought about the destruction of the haddock, a more important stock for the Scottish fishing industry. The Belgian government has already announced a tie-up scheme, partly financed from European Union funds, to protect immature sole.

 Fishermen have submitted proposals to the Scottish Office and Ministry of Agriculture for a £100 million scheme for tie-ups and for decommissioning boats. The association will hold a meeting this weekend which will call on the Government to close the areas now being over-fished.

 All the vessels fishing for juvenile haddock are using the new square mesh panels, now a legal requirement, but these do not allow more than 10 per cent of the fish to escape. A spokesman for the Scottish Executive said: "We are well aware of the situation. We are faced with the difficulty that what is going on is not illegal and we believe it underlines the importance of technical conservation measures. We have received proposals for a package, including a tie-up scheme, which we are considering."

 Scientists at Aberdeen fisheries laboratory said the number of fish being taken at present was above the level agreed by the Union and the Norwegian government last year.